The oscillators that are used in a digital to analog converter (DAC) and an analog to digital converter (ADC) at the sampling instants for the transmitter and the receiver do not ordinarily have the exact same period. Accordingly, the sampling instants tend to shift relative to one another, causing a sampling clock error.
This sampling clock error has a number of negative effects. It causes a slow shift of the timing symbol point, which in turn, rotates the subcarriers. Also, there may be a loss of signal to noise ratio (SNR) due to intercarrier interference (ICI) generated by the slightly incorrect sampling instants, which causes loss of the orthogonality of the subcarriers.
One possible way to correct the rotation of the subcarriers caused by the sampling frequency offset is by adjusting the sample frequency of the DAC of the receiver. However, adjusting the sampling clock requires an adjustment to a complicated analog part of the receiver, and analog components are relatively costly in comparison to digital solutions.
Accordingly, it would be advantageous to provide an efficient and more cost effective method and apparatus to correct the effects of sampler clock frequency offset in orthogonal frequency division multiplexed (OFDM) systems.